Typically, a wall-mounted air conditioner includes a crossflow fan as an air blower. As shown in FIG. 24, a crossflow fan 104 is a transverse flow air blower (a through flow air blower). The crossflow fan 104 causes the air to flow through an impeller 141 in such a manner as to cross a plane perpendicular to the rotation axis Z of the impeller 141. The impeller 141 is formed by a plurality of blades (flaps) 142. The impeller 141 rotates in the direction indicated by arrow Z1 in FIG. 24. As a result, after having been cooled or heated by the air conditioner, the air passes through the impeller 141 and is then blown out into the room in which the air conditioner is mounted. Patent Document 1 discloses a blade having a plurality of cutouts that are formed in the outer periphery of the blade and spaced apart at predetermined intervals to reduce noise produced by a fan.
Specifically, with reference to FIGS. 25 and 26, blades 242, which configure an impeller 241, each include an outer peripheral edge 243 and an inner peripheral edge 244. The outer peripheral edges 243 are arranged at the centrifugal side of the impeller 241 and the inner peripheral edges 244 are located at the rotation axis side of the impeller 241. Each of the outer peripheral edges 243 has a plurality of cutouts 245, which are spaced apart at predetermined intervals. As a result, each of the blades 242 has cut portions 246, which are cut in the outer peripheral edge 243, and basic shape portions 247, each of which is formed between the corresponding adjacent pair of the cut portions 246 as a non-cut portion in the outer peripheral edge 243.
Recently, it has been desired to save energy consumed by crossflow fans. However, although noise is reduced by a simple configuration such as cutouts formed in blades like those in the blades of Patent Document 1, the power produced by an electric motor that is necessary for rotating an impeller, which is the drive power for a crossflow fan, cannot be reduced sufficiently.